Abstract:

A substrate processing apparatus capable of preventing the abnormal
discharge from being generated on a substrate. A housing chamber houses
the substrate. A mounting stage arranged in the housing chamber, is
configured to enable the substrate to be mounted thereon. A disc-like
electrode structure is connected to a high-frequency power supply, and
connected to a gas supply apparatus via at least one gas supply system.
The electrode structure has therein at least one buffer chamber and a
plurality of connecting sections connected to the gas supply system. The
buffer chamber is communicated with the inside of the housing chamber via
a number of gas holes, and is communicated with the gas supply system via
the plurality of connecting sections. The plurality of connecting
sections for the buffer chamber are arranged on the circumference of a
circle centering around the center of the electrode structure at equal
intervals.

Claims:

1. A substrate processing apparatus comprising:a housing chamber
configured to house a disc-like substrate;a mounting stage arranged in
said housing chamber and configured to enable the substrate to be mounted
thereon;a high-frequency power supply;a gas supply apparatus configured
to supply processing gas; anda disc-like electrode structure connected to
said high-frequency power supply, and connected to said gas supply
apparatus via at least one gas supply system;wherein the electrode
structure is arranged opposite to said mounting stage, and has therein at
least one buffer chamber and a plurality of connecting sections connected
to the gas supply system,wherein the buffer chamber is communicated with
the inside of said housing chamber via a number of gas holes, and is
communicated with the gas supply system via the plurality of connecting
sections, andwherein the plurality of connecting sections for the buffer
chamber are arranged on the circumference of a circle centering around
the center of said electrode structure at equal intervals.

2. The substrate processing apparatus according to claim 1,wherein said
electrode structure has therein a plurality of buffer chambers,
andwherein when the total number of the connecting sections corresponding
to all the buffer chambers is set to n, the each connecting section is
arranged at each rotational angle of 360.degree./n.+-.3.degree. around
the center of said electrode structure.

3. The substrate processing apparatus according to claim 1,wherein said
electrode structure is configured by a ceiling electrode plate, a cooling
plate, and an upper electrode body which are stacked in this order from
the side of the housing chamber, and the ceiling electrode plate, the
cooling plate, and the upper electrode body are made of a conductive
material, andwherein the plurality of connecting sections are arranged on
the upper electrode body, and the upper electrode body is connected to
said high-frequency power supply.

4. The substrate processing apparatus according to claim 1, wherein at
least a portion of the gas supply system, which portion is connected to
the connecting section, is made of an insulating material.

5. An electrode structure provided in a substrate processing apparatus
which includes: a housing chamber configured to house a disc-like
substrate; a mounting stage arranged in the housing chamber and
configured to enable the substrate to be mounted thereon; a
high-frequency power supply; and a gas supply apparatus configured to
supply processing gas,wherein said electrode structure has a disc-like
shape, and is connected to the high-frequency power supply, and connected
to the gas supply apparatus via at least one gas supply system,wherein
said electrode structure is arranged opposite to the mounting stage, and
has therein at least one buffer chamber and a plurality of connecting
sections connected to the gas supply system,wherein the each buffer
chamber is communicated with the inside of the housing chamber via a
number of gas holes, and is communicated with the gas supply system via
the plurality of connecting sections, andwherein the plurality of
connecting sections for the each buffer chamber are arranged on the
circumference of a circle centering around the center of the electrode
structure at equal intervals.

Description:

BACKGROUND OF THE INVENTION

[0001]1. Field of the Invention

[0002]The present invention relates to a substrate processing apparatus
and an electrode structure, and more particularly to a substrate
processing apparatus including an electrode structure which is connected
to a high-frequency power supply and to a gas supply apparatus adapted to
supply processing gas.

[0003]2. Description of the Related Art

[0004]As a substrate processing apparatus 60 adapted to perform plasma
processing, for example, etching processing to a wafer W as a substrate,
there is known, as shown in FIG. 6, an apparatus configured by including:
a chamber 61 which houses the wafer W; a mounting stage 62 which is
arranged in the chamber 61 and on which the wafer W is mounted; and a
disc-like shower head 63 which is arranged opposite to the mounting stage
62, and which introduces processing gas into the chamber 61. In the
substrate processing apparatus 60, high-frequency power supplies 64 and
65 are respectively connected to the mounting stage 62 and the shower
head 63, which also function as electrodes. Then, the mounting stage 62
and the shower head 63 supply high-frequency power to the inside of the
chamber 61, so that an electric field is generated in the chamber 61. The
electric field generates plasma from the processing gas, so that the
plasma performs plasma processing to the wafer W.

[0005]Meanwhile, in order to perform the plasma processing uniformly to
the wafer W, it is necessary to make uniform the distribution of plasma
density on the wafer W. However, in order to make uniform the
distribution of plasma density, it is necessary to make uniform the
distribution of the electric field. Thus, for example, as in the
substrate processing apparatus 60, there has been developed a substrate
processing apparatus 60 in which branching waveguides (power supply
tubes) 66 connected to the high-frequency power supply 65 and connected
to the shower head 63 symmetrically around the center of the shower head
63 are provided, to thereby make uniform the distribution of the electric
field (for example, see Japanese Patent Laid-Open Publication No.
8-325759).

[0006]Further, the distribution of plasma density is influenced by the
distribution of processing gas introduced from the shower head.
Accordingly, it is known that as shown in FIG. 7, in an electrode
structure 70 of the substrate processing apparatus, two mutually
separated buffer chambers 72a and 72b are provided in a shower head 71,
and a gas supply apparatus (not shown) for supplying processing gas is
connected to each of the buffer chambers 72a and 72b via separate gas
supply systems 73a and 73b, respectively, so as to control the flow rate
of the processing gas in each of the gas supply systems 73a and 73b. In
the electrode structure 70, each of the buffer chambers 72a and 72b is
communicated with the inside of the chamber which houses a wafer, and the
flow rate of the processing gas supplied to the inside of the buffer
chambers 72a and 72b is controlled, so as to enable the shower head 71 to
control the distribution of the processing gas introduced into the
chamber.

[0007]Note that in the electrode structure 70, connecting sections 74a and
74b, which respectively connect the gas supply systems 73a and 73b to the
buffer chambers 72a and 72b, are arranged at the same angle with respect
to the center of the shower head 71, that is, in the same radial
direction.

[0008]However, when the etching processing is performed to the wafer W by
using the above described electrode structure 70 shown in FIG. 7, micro
abnormal discharge (arcing) has been sometimes generated on the wafer W.
Specifically, the arcing has been generated at the positions symmetrical
with the positions at which the connecting sections 74a and 74b are
arranged, with respect to the center of the shower head 71. The arcing
may destroy a wiring and an insulating film of the semiconductor device
which are formed on the wafer W, and hence it is necessary to prevent the
generation of the arcing.

SUMMARY OF THE INVENTION

[0009]The present invention provides a substrate processing apparatus and
an electrode structure which are capable of preventing the abnormal
discharge from being generated on the substrate.

[0010]Accordingly, in a first aspect of the present invention, there is
provided a substrate processing apparatus comprising a housing chamber
configured to house a disc-like substrate, a mounting stage arranged in
the housing chamber and configured to enable the substrate to be mounted
thereon, a high-frequency power supply, a gas supply apparatus configured
to supply processing gas, and a disc-like electrode structure connected
to the high-frequency power supply, and connected to the gas supply
apparatus via at least one gas supply system, wherein the electrode
structure is arranged opposite to the mounting stage, and has therein at
least one buffer chamber and a plurality of connecting sections connected
to the gas supply system, wherein the buffer chamber is communicated with
the inside of the housing chamber via a number of gas holes, and is
communicated with the gas supply system via the plurality of connecting
sections, and wherein the plurality of connecting sections for the buffer
chamber are arranged on the circumference of a circle centering around
the center of the electrode structure at equal intervals.

[0011]According to the first aspect of the present invention, in the each
buffer chamber provided in the electrode structure connected to the
high-frequency power supply, the plurality of connecting sections
connected to the at least one gas supply system are arranged on the
circumference of a circle centering around the center of the electrode
structure at equal intervals. This enables the processing gas to be
uniformly supplied to the inside of the each buffer chamber, so that the
distribution of the processing gas introduced into the housing chamber
via the each buffer chamber can be made uniform. Also, this enables the
structure of the electrode structure to be made symmetrical about the
center of the electrode structure, so that the distribution of the
electric field generated in the housing chamber can be made uniform. As a
result, the distribution of plasma density on the substrate can be made
uniform, so that the generation of the abnormal discharge on the
substrate can be prevented.

[0012]The first aspect of the present invention can provide a substrate
processing apparatus, wherein the electrode structure has therein a
plurality of buffer chambers, and wherein when the total number of the
connecting sections corresponding to all the buffer chambers is set to n,
the each connecting section is arranged at each rotational angle of
360°/n±3° around the center of the electrode structure.

[0013]According to the first aspect of the present invention, when the
total number of the connecting sections corresponding to all the buffer
chambers is set to n, the each connecting section is arranged at each
rotational angle of 360°/n±3° about the center of the
electrode structure. Thereby, the distribution of the processing gas
introduced into the housing chamber via the each buffer chamber can be
made more uniform, and the structure of the electrode structure can be
made more symmetrical.

[0014]The first aspect of the present invention can provide a substrate
processing apparatus, wherein the electrode structure is configured by a
ceiling electrode plate, a cooling plate, and an upper electrode body
which are stacked in this order from the side of the housing chamber, and
the ceiling electrode plate, the cooling plate, and the upper electrode
body are made of a conductive material, and wherein the plurality of
connecting sections are arranged on the upper electrode body, and the
upper electrode body is connected to the high-frequency power supply.

[0015]According to the first aspect of the present invention, the
plurality of connecting sections are arranged on the upper electrode body
connected to the high-frequency power supply, and hence the structure of
the upper electrode body to which the high-frequency power is supplied
can be made symmetrical. Thereby, the distribution of the electric field
generated in the housing chamber can be surely made uniform.

[0016]The first aspect of the present invention can provide a substrate
processing apparatus, wherein at least a portion of the gas supply
system, which portion is connected to the connecting section, is made of
an insulating material.

[0017]According to the first aspect of the present invention, at least a
portion of the gas supply system, which portion is connected to the
connecting section, is made of an insulating material, and hence the gas
supply system does not affect the distribution of the electric field.
Thereby, the distribution of the electric field generated in the housing
chamber can be more surely made uniform.

[0018]Accordingly, in a second aspect of the present invention, there is
provided an electrode structure provided in a substrate processing
apparatus which includes a housing chamber configured to house a
disc-like substrate, a mounting stage arranged in the housing chamber and
configured to enable the substrate to be mounted thereon, a
high-frequency power supply, and a gas supply apparatus configured to
supply processing gas, wherein the electrode structure has a disc-like
shape, and is connected to the high-frequency power supply, and connected
to the gas supply apparatus via at least one gas supply system, wherein
the electrode structure is arranged opposite to the mounting stage, and
has therein at least one buffer chamber and a plurality of connecting
sections connected to the gas supply system, wherein the each buffer
chamber is communicated with the inside of the housing chamber via a
number of gas holes, and is communicated with the gas supply system via
the plurality of connecting sections, and wherein the plurality of
connecting sections for the each buffer chamber are arranged on the
circumference of a circle centering around the center of the electrode
structure at equal intervals.

[0019]The features and advantages of the invention will become more
apparent from the following detailed description taken in conjunction
with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020]FIG. 1 is a sectional view schematically showing a configuration of
a substrate processing apparatus according to an embodiment of the
present invention.

[0021]FIG. 2 is a plan view schematically showing a positional relation
between the shower head, the clamp, the central gas supply system, and
the peripheral gas supply system shown in FIG. 1.

[0022]FIG. 3 is a sectional view schematically showing a configuration of
a variation of the electrode structure according to the present
embodiment.

[0023]FIG. 4A and FIG. 4B are graphs showing the etching rate distribution
at the time when etching processing is performed to an oxide film on a
wafer by using the substrate processing apparatus according to the
present embodiment and a conventional substrate processing apparatus:
FIG. 4A shows the etching rate distribution at the time when the
conventional substrate processing apparatus is used; and FIG. 4B shows
the etching rate distribution at the time when the substrate processing
apparatus according to the present embodiment is used.

[0024]FIG. 5A and FIG. 5B are graphs showing the etching rate distribution
at the time when etching processing is performed to a photoresist film on
the wafer by using the substrate processing apparatus according to the
present embodiment and the conventional substrate processing apparatus:
FIG. 5A shows the etching rate distribution at the time when the
conventional substrate processing apparatus is used; and FIG. 5B shows
the etching rate distribution at the time when the substrate processing
apparatus according to the present embodiment is used.

[0025]FIG. 6 is a sectional view schematically showing a configuration of
the conventional substrate processing apparatus.

[0026]FIG. 7 is a plan view schematically showing a configuration of the
conventional electrode structure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027]In the following, embodiments according to the present invention
will be described with reference to the accompanying drawings.

[0028]First, a substrate processing apparatus according to an embodiment
of the present invention will be described.

[0029]FIG. 1 is a sectional view schematically showing a configuration of
a substrate processing apparatus according to an embodiment of the
present invention. The substrate processing apparatus is configured such
that etching processing as plasma processing is performed to a
semiconductor wafer as a substrate.

[0030]In FIG. 1, the substrate processing apparatus 10 has, for example, a
chamber 11 (housing chamber) which houses a disc-like semiconductor wafer
(hereinafter referred to as simply "wafer") W having a diameter of 300
mm. A cylindrical susceptor supporting stage 12 is arranged on the bottom
surface inside the chamber 11, and a cylindrical susceptor 13 (mounting
stage) is arranged on the susceptor supporting stage 12.

[0031]An ESC (Electrostatic Chuck) 14 (mounting stage) is arranged on the
susceptor 13. The ESC 14 is made of, for example, aluminum. A ceramic
material such as alumina, or the like, is thermally sprayed onto the
upper surface of the ESC 14 to form a thermally sprayed film (not shown).
In the thermally sprayed film, there is provided an electrostatic
electrode plate 16 to which a DC power supply 15 is electrically
connected.

[0032]The wafer W housed in the chamber 11 is mounted on the upper surface
(hereinafter referred to as "mounting surface") of the ESC 14. When a
positive DC voltage is applied to the electrostatic electrode plate 16
from the DC power supply 15, a negative potential is generated in the
contact surface of the wafer W in contact with the mounting surface, to
cause a potential difference between the electrostatic electrode plate 16
and the contact surface of the wafer W. As a result, the wafer W is
attracted to be held on the mounting surface of the ESC 14 by the Coulomb
force or Johnson Rahbeck force resulting from the potential difference.

[0033]A plurality of heat transfer gas supply holes 17 are opened in the
mounting surface of the ESC14. The plurality of heat transfer gas supply
holes 17 are connected to a heat transfer gas supply section (not shown)
via a heat transfer gas supply line 18. The heat transfer gas supply
section supplies helium (He) gas as the heat transfer gas between the
contact surface of the wafer W and the mounting surface via the heat
transfer gas supply holes 17. The helium gas supplied to the gap between
the contact surface of the wafer W and the mounting surface effectively
transfers the heat of the wafer W to the ESC 14.

[0034]The susceptor 13 is made of, for example, an aluminum alloy, and is
connected to a lower high-frequency power supply 19 via a lower matching
box (Matcher) 20, and the lower high-frequency power supply 19 supplies
high-frequency power of relatively low frequency to the susceptor 13.
Thereby, the susceptor 13 functions as a lower electrode for supplying
the high-frequency power to a processing space S which is a space between
the susceptor 13 and a shower head 24 as will be described below.
Further, the lower matching box 20 matches the internal impedance of the
lower high-frequency power supply 19 with a load impedance.

[0035]Inside the susceptor supporting stage 12, for example, there is
provided an annular coolant chamber 21 extending in the circumferential
direction. To the coolant chamber 21, low-temperature coolant such as,
for example, cooling water and Galden (registered trademark) fluid is
circulated and supplied via a coolant pipe 22 from a chiller unit (not
shown). The susceptor supporting stage 12 cooled by the low-temperature
coolant cools the wafer W via the ESC 14.

[0036]Further, an annular focus ring 23 is arranged on the ESC 14. The
focus ring 23 is made of a conductive material such as, for example,
silicon, and surrounds the wafer W which is attracted to be held on the
mounting surface of the ESC 14. Further, the focus ring 23 converges
plasma generated in the processing space S to the surface of the wafer W,
to thereby improve the efficiency of the etching processing.

[0037]The disc-like shower head 24 (electrode structure) is arranged in
the ceiling section of the chamber 11, so as to face the wafer W mounted
on the ESC 14. The shower head 24 has a ceiling electrode plate 25, a
cooling plate 26, and an upper electrode supporting body 27 (upper
electrode body) which are stacked in this order from the side of the
processing space S. An upper high-frequency power supply 30 is connected
to the upper electrode supporting body 27 via a power supply tube 28 and
an upper matching box 29. The upper high-frequency power supply 30
supplies high-frequency power of a relatively high frequency to the upper
electrode supporting body 27. The ceiling electrode plate 25, the cooling
plate 26, and the upper electrode supporting body 27 are made of a
conductive material such as, for example, an aluminum alloy, and hence
the high-frequency power supplied to the upper electrode supporting body
27 is supplied to the processing space S via the cooling plate 26 and the
ceiling electrode plate 25. That is, the shower head 24 functions as an
upper electrode for supplying the high-frequency power to the processing
space S. Note that the function of the upper matching box 29 is the same
as the function of the above described lower matching box 20.

[0038]Note that the outer periphery of the shower head 24 is covered by an
annular dielectric member 31 which insulates the shower head 24 from the
wall of the chamber 11. Further, the outside of the power supply tube 28
is covered by a case-shaped grounding conductive member 32, and the power
supply tube 28 penetrates the upper-surface central portion of the
grounding conductive member 32. In the penetrating section, an insulating
member 33 is provided between the grounding conductive member 32 and the
power supply tube 28.

[0039]Further, in the shower head 24, the cooling plate 26 has, in the
inside thereof, a central buffer chamber 34 formed of a disc-like space
centering on the center (hereinafter referred to as "shower head center")
of the shower head 24, and a peripheral buffer chamber 35 formed of an
annular space concentric with the central buffer chamber 34. The central
buffer chamber 34 and the peripheral buffer chamber 35 are separated by
an annular partition wall member such as, for example, an O ring 37.
Further, the cooling plate 26 and the ceiling electrode plate 25 have a
number of penetrating gas holes 36 through which the central buffer
chamber 34 and the peripheral buffer chamber 35 are communicated with the
processing space S.

[0040]Further, in the shower head 24, a plurality of clamps 38 and 40
(connecting sections) made of a conductive material such as, for example,
aluminum are arranged on the upper electrode supporting body 27.
Specifically, two clamps 38 are arranged at positions corresponding to
the central buffer chamber 34, and two clamps 40 are arranged at
positions corresponding to the peripheral buffer chamber 35. The two
clamps 38 are connected to a central gas supply system 39 consisting of
two branched pipes. The two clamps 40 are connected to a peripheral gas
supply system 41 consisting of two branched pipes. Note that in the
central gas supply system 39 and the peripheral gas supply system 41, the
portions respectively connected to the clamps 38 and 40, specifically,
the portions existing in the inside of the grounding conductive member
32, are made of an insulating material, specifically, a resin.

[0041]The central buffer chamber 34 is communicated with the central gas
supply system 39 via the two clamps 38, and the peripheral buffer chamber
35 is communicated with the peripheral gas supply system 41 via the two
clamps 40. Note that the central gas supply system 39 and the peripheral
gas supply system 41 are connected to a branch flow rate adjusting
apparatus 42 which adjusts the flow rates of the mixture of processing
gas and additional gas to the central gas supply system 39 and the
peripheral gas supply system 41, respectively. The branch flow rate
adjusting apparatus 42 is connected to a processing gas supply apparatus
for supplying the processing gas, and to an additional gas supply
apparatus for supplying the additional gas (both not shown). Note that
the processing gas in the present embodiment corresponds to, for example,
CF-based gas and oxygen gas, and the additional gas corresponds to, for
example, argon gas.

[0042]In the shower head 24, the mixed gas containing the processing gas
is introduced into the central buffer chamber 34 and the peripheral
buffer chamber 35 from the branch flow rate adjusting apparatus 42 via
the central gas supply system 39 and the peripheral gas supply system 41.
The introduced mixed gas is introduced into the processing space S via a
number of the penetrating gas holes 36. Therefore, the shower head 24
functions as a gas introducing device. Further, in the shower head 24, a
coolant chamber (not shown) is provided in the cooling plate 26. A
coolant such as, for example, cooling water and Galden (registered
trademark) fluid introduced from coolant introducing sections 43a and 43b
as will be described below, is supplied to the inside of the coolant
chamber. The cooling plate 26 cools the mixed gas introduced into the
central buffer chamber 34 and the peripheral buffer chamber 35 by the
coolant in the coolant chamber.

[0043]In the present embodiment, the mixed gas introduced from the
penetrating gas holes 36 corresponding to the peripheral buffer chamber
35 is distribution-diffused toward the periphery of the wafer W mounted
on the mounting surface, and the mixed gas introduced from the
penetrating gas holes 36 corresponding to the central buffer chamber 34
is distribution-diffused toward the central portion of the wafer W
mounted on the mounting surface. Note that the density distribution of
the mixed gas on the wafer W can be adjusted by adjusting the flow rate
of the mixed gas which is distributed to each of the central gas supply
system 39 and the peripheral gas supply system 41 by the branch flow rate
adjusting apparatus 42.

[0044]FIG. 2 is a plan view schematically showing a positional relation
between the shower head, the clamps, the central gas supply system, and
the peripheral gas supply system, which are shown in FIG. 1.

[0045]In FIG. 2, the two clamps 38 corresponding to the central buffer
chamber 34 are arranged on the circumference of a circle centering around
the shower head center at equal intervals, specifically, at each
180°±3°. Further, the central buffer chamber 34 is
formed of a disc-like space centering on the shower head center.
Therefore, in the central buffer chamber 34, the mixed gas is introduced
symmetrically around the shower head center. As a result, the mixed gas
can be uniformly supplied into the central buffer chamber 34.

[0046]Further, the two clamps 40 corresponding to the peripheral buffer
chamber 35 are also arranged on the circumference of a circle centering
around the shower head center at equal intervals, specifically, at each
180°±3°. The peripheral buffer chamber 35 is formed of
an annular space centering around the shower head center.

[0047]Therefore, also in the peripheral buffer chamber 35, the mixed gas
is introduced symmetrically around the shower head center. As a result,
the mixed gas can be uniformly supplied to the inside of the peripheral
buffer chamber 35.

[0048]Further, in the shower head 24, the total number of the clamps 38
and 40 is four, and each of the clamps 38 and 40 is arranged at each
rotational angle of 360°/4±3° in the rotational system
centering around the shower head center. Specifically, the rotational
angle between the adjacent clamps 38 and 40, which angle centers around
the shower head center, is 90°±3°. Thereby, the mixed
gas can be symmetrically introduced into the processing space S via the
central buffer chamber 34 and the peripheral buffer chamber 35.
Therefore, the distribution of the mixed gas introduced into the
processing space S can be made more uniform.

[0049]Note that in the shower head 24, the coolant introducing sections
43a and 43b, and a PT sensor 44 which is a temperature measuring sensor,
are arranged so as to avoid the clamps 38 and 40, the central gas supply
system 39, and the peripheral gas supply system 41.

[0050]Returning to FIG. 1, in the substrate processing apparatus 10, a
high pass filter 45 is electrically connected to the susceptor 13, and
the high pass filter 45 passes the high-frequency power from the upper
high-frequency power supply 30 to the ground. Further, a low pass filter
46 is electrically connected to the shower head 24, and the low pass
filter 46 passes the high-frequency power from the lower high-frequency
power supply 19 to the ground.

[0051]Further, in the substrate processing apparatus 10, a flow path,
through which the gas above the ESC 14 is discharged to the outside of
the chamber 11, is formed between the inside wall of the chamber 11 and
the side surface of the ESC 14 (susceptor 13), and an exhaust plate 47 is
arranged in the middle of the flow path. The exhaust plate 47 is a
plate-shaped member having a number of holes, and captures or reflects
the plasma generated in the processing space S, so as to prevent the
leakage of the plasma.

[0052]In the substrate processing apparatus 10, when the mixed gas is
introduced into the processing space S from the shower head 24, and when
the high-frequency power is supplied to the processing space S from the
susceptor 13 and the shower head 24, a high frequency electric field is
generated in the processing space S, so that the processing gas in the
mixed gas is excited to become plasma. The plasma performs etching
processing to the wafer W.

[0053]Note that the operation of each component of the above described
substrate processing apparatus 10 is controlled by a CPU of a controller
(not shown) provided in the substrate processing apparatus 10 on the
basis of a program corresponding to the etching processing.

[0054]According to the substrate processing apparatus 10 of the present
embodiment, the two clamps 38 corresponding to the central buffer chamber
34 and connected to the central gas supply system 39 are arranged on the
circumference of a circle centering around the shower head center at
equal intervals. Further, the two clamps 40 corresponding to the
peripheral buffer chamber 35 and connected to the peripheral gas supply
system 41 are arranged on the circumference of a circle centering around
the shower head center at equal intervals. Thereby, the processing gas
can be uniformly supplied into the central buffer chamber 34 and the
peripheral buffer chamber 35, so that it is possible to make uniform the
distribution of the processing gas introduced into the processing space S
via the central buffer chamber 34 and the peripheral buffer chamber 35.
Further, the structure of the shower head 24 which supplies
high-frequency power to the processing space S can be made symmetrical
with respect to the shower head center, so that it is possible to make
uniform the distribution of the electric field generated in the
processing space S. As a result, the distribution of the density of
plasma generated on the wafer W can be made uniform, so that it is
possible to prevent the generation of arcing on the wafer W.

[0055]In the above described substrate processing apparatus 10, the total
number of the clamps 38 and 40 is four, and hence the clamps 38 and 40
are arranged at each rotational angle of 90°±3° around
the shower head center. Therefore, the distribution of the processing gas
introduced into the processing space S can be made more uniform. Further,
the structure of the shower head 24 can be made more symmetrical with
respect to the shower head center.

[0056]Further, in the above described substrate processing apparatus 10,
the four clamps 38 and 40 are arranged on the upper electrode supporting
body 27 connected to the upper high-frequency power supply 30, and hence
the structure formed by the upper electrode supporting body 27 to which
the high-frequency power is supplied, and formed by the four clamps 38
and 40 can be made symmetrical. Thereby, the distribution of the electric
field generated in the processing space S can be surely made uniform.

[0057]Further, in the above described substrate processing apparatus 10,
the portions of the central gas supply system 39 and the peripheral gas
supply system 41, which portions are respectively connected to the clamps
38 and 40, are made of a resin, and hence the high-frequency power
supplied to the upper electrode supporting body 27 is prevented from
being transmitted to the central gas supply system 39 and the peripheral
gas supply system 41 via the clamps 38 and 40. Therefore, the central gas
supply system 39 and the peripheral gas supply system 41 do not affect
the distribution of the electric field in the processing space S, so that
the distribution of the electric field generated in the processing space
S can be more surely made uniform.

[0058]In the above described embodiment, two clamps are arranged on the
upper electrode supporting body 27 in correspondence with each of the
buffer chambers, but the number of the clamps arranged in correspondence
with each of the buffer chambers is not limited to two. For example, the
number of the clamps may be three or more. In this case, N clamps
corresponding to each of the buffer chambers are arranged on the
circumference of a circle centering around the shower head center at
equal intervals, specifically, at each 360°/N.

[0059]Further, the number of the buffer chambers provided in the shower
head 24 is not limited to two, but the number of the buffer chambers may
be one, or three or more. Even in this case, when the total number of the
clamps arranged on the upper electrode supporting body 27 is set to n,
the clamps are arranged at each rotational angle of
360°/n±3° in the rotational system centering around the
shower head center. For example, as shown in FIG. 3, when the shower head
24 has three buffer chambers, and when the number of the clamps arranged
on the upper electrode supporting body 27 in correspondence with each of
the buffer chambers is two, the total number of the clamps is 6, and
hence the clamps are arranged at each rotational angle of
60°±3° in the rotational system centering around the
shower head center.

[0060]Further, in the above described embodiment, the coolant introducing
sections 43a and 43b are not symmetrically arranged with respect to the
shower head center. However, in the upper electrode supporting body 27,
the two coolant introducing sections may be symmetrically arranged.
Specifically, the two coolant introducing sections may be arranged at
equal intervals on the circumference of a circle centering around the
shower head center, for example, at each 180°±3°.
Thereby, the structure of the shower head 24 can be made still more
symmetrical about the shower head center, so that the distribution of the
electric field generated in the processing space S can be surely made
uniform. Further, the plurality of components arranged on the upper
electrode supporting body 27 may be preferably arranged as symmetrically
as possible with respect to the shower head center.

[0061]Note that in the above described embodiment, the location tolerance
in the arrangement of the clamps and the like is set to ±3°.
However, the general machining tolerance is also in general
±3°, and hence special tolerance management to realize the
above described arrangement of the clamps and the like is not needed.
Thereby, it is possible to prevent the increase in manufacturing cost of
the shower head 24.

EXAMPLE

[0062]Next, an example according to the present invention will be
specifically described.

EXAMPLE

[0063]First, when it was observed whether or not arcing was generated on a
wafer W during the etching processing performed to the wafer W in the
substrate processing apparatus 10, the generation of the arcing was not
observed. Further, when the charge distribution on the surface of the
wafer W was investigated, it was confirmed that the charges were
distributed in the state of concentric circles, and that uneven
distribution of the charges in the circumferential direction was not
generated.

[0064]Further, the etching processing was performed to the oxide film on
the wafer W in the substrate processing apparatus 10, and the
distribution of etching rate at this time was observed. The observation
result is shown in the graph of FIG. 4B. Further, the etching processing
was performed to the photoresist film on the wafer W in the substrate
processing apparatus 10, and the distribution of etching rate at this
time was observed. The observation result is shown in the graph of FIG.
5B.

COMPARISON EXAMPLE

[0065]First, when it was observed whether or not arcing was generated on a
wafer W during the etching processing performed to the wafer W in the
substrate processing apparatus (hereinafter referred to as "conventional
substrate processing apparatus") provided with the electrode structure 70
shown in FIG. 7, it was confirmed that the arcing was generated at
positions symmetrical with the positions at which the connecting sections
74a and 74b are arranged, with respect to the center of the shower head
71. Further, when the charge distribution on the surface of the wafer W
was investigated, it was confirmed that uneven distribution of the
charges was generated at positions symmetrical with the positions at
which the connecting sections 74a and 74b are arranged, with respect to
the center of the shower head 71.

[0066]Further, the etching processing was performed to the oxide film on
the wafer W in the conventional substrate processing apparatus, the
distribution of etching rate at this time was observed. The observation
result is shown in the graph of FIG. 4A. Further, the etching processing
was performed to the photoresist film on the wafer W in the conventional
substrate processing apparatus, the distribution of etching rate at this
time was observed. The observation result is shown in the graph of FIG.
5A.

[0067]By comparing Example with Comparison Example, it was seen that in
Comparison Example, the arcing was generated, and the uneven distribution
of the charges was also generated, while in Example, the arcing was not
generated, and also the uneven distribution of the charges was not
generated. From this fact, it was seen that in Example, the distribution
of the processing gas introduced into the processing space S was made
uniform, and the distribution of the electric field generated in the
processing space S was also made uniform, as a result of which the
distribution of the density of plasma generated on the wafer W was made
uniform.

[0068]In addition, the graph of FIG. 4A was compared with the graph of
FIG. 4B, and further the graph of FIG. 5A was compared with the graph of
FIG. 5B. As a result, it was seen that in any of the etching processing
of the oxide film and the etching processing of the photoresist film, the
dispersion in the distribution of etching rate in Example is smaller than
the dispersion in the distribution of etching rate in Comparison Example.
Also from this fact, it was seen that in Example, the distribution of the
density of plasma generated on the wafer W was made uniform.